The 'Live While We're Young' singer was first linked to Irish model back in March this year but things are said to have ended over Niall's busy touring schedule as well as alleged pressure from his camp.

"It's all over for Niall and Zoe, and it is completely because of his side of things," a source told The Mirror this weekend. "Obviously it was always going to be hard to have an ongoing relationship when his job has him travelling around so much.

"But there's been no push from Niall to keep things going at all and has told Zoe it is over by completely blanking her," the source explained. "Out of respect to Niall she refused to say a word to anyone about the relationship, even when there was money on the table to spill the beans, as she knew it would be over then.

"But it seems just doing her job is too much for 1D's people, who appear to have pressured Niall to cut all ties with Zoe," they added, referring to her growing career as a model.

Check out a picture of Niall working out in the gym out on the band's US tour this month below (Credit: Twitter):

The 'Little Things' singer was also briefly linked with Made In Chelsea star Louise Thompson last month, despite declaring himself a "single pringle" only several weeks ago.

One Direction return with new single 'Best Song Ever' on 22nd July with 3D concert movie This Is Us arriving in cinemas this August.